As one type of power MOS (metal oxide semiconductor) field effect transistors, the lateral DMOS (double diffused metal oxide semiconductor) field effect transistor is known.
In DMOS field effect transistors, typically, the measure to extend the length of the drift region (drift length) is taken to increase the device breakdown voltage. In terms of device layout, the measure to increase the breakdown voltage is often taken in the device termination region rather than in the internal region of the device (device active region). This is because, despite elaborate design of the internal region (device active region) relevant to device characteristics, the device characteristics are difficult to control if there is the possibility of decreasing the device breakdown voltage in the device termination region not affecting the device characteristics. However, if the measure to extend the drift length is taken as described above to increase the breakdown voltage of the device termination region, the lateral DMOS field effect transistor has the problem of increased device area.